1. Field of the Invention
The present invention relates to a group of compounds classified in the field or organic chemistry as 3-[(substituted-amino)(aryl or heteroaryl)methyl]-1H-indoles which are useful as color formers in pressure-sensitive carbonless duplicating systems and thermal marking systems; to processes for the preparation thereof and to pressure-sensitive carbonless duplicating systems and thermal marking systems containing the same.
2. Description of the Prior Art
Several classes of organic compounds of widely diverse structural types are known to be useful as color formers for carbonless duplicating systems. Among the most widely recognized classes are the phenothiazines, for example, benzoyl leuco methylene blue; fluorans, for example, 2'-anilino-6'-diethylaminofluoran; phthalides, for example, crystal violet lactone; methine dyes, for example, Michler's hydrol and derivatives thereof and various other types of color formers currently employed in commercially accepted carbonless duplicating systems. Typical of the many such systems taught in the prior art are those described in U.S. Pat. Nos. 2,712,507, 2,800,457 and 3,041,289, which issued July 5, 1955, July 23, 1957 and June 26, 1962, respectively. Many of the color formers in the prior art suffer one or more disadvantages such as low tinctorial strength, poor light stability, poor xerographic copiability, low resistance to sublimation, and low solubility in common organic solvents, the latter disadvantage thus requiring the use of specialized and expensive solvents in order to obtain microencapsulated solutions of sufficient concentration for use in pressure-sensitive copying systems.
The following appear to constitute the most relevant prior art relative to the present invention.
U.S. Pat. No. 3,958,815 issued May 25, 1976 discloses in most pertinent part a group of compounds stated to be useful as dye precursors in pressure-sensitive recording materials and having the formula ##STR1## wherein inter alia R.sub.1 and R.sub.2 represent (1) an aryl group substituted with an ether group R.sub.6 --O-- in which R.sub.6 represents a hydrocarbon group or (2) a heterocyclic group; R.sub.3 represents NR.sub.8 R.sub.9 in which each of R.sub.8 and R.sub.9 (same or different) represents hydrogen or an alkyl group, a cycloalkyl group, an aralkyl group or an aryl group, or R.sub.8 and R.sub.9 together represent the necessary atoms to close a nitrogen-containing heterocyclic nucleus, and m and n are 0.
French Pat. No. 1,561,663 published Mar. 28, 1969 discloses in most pertinent part a series of compounds having the formula ##STR2## wherein inter alia R.sub.1 and R.sub.2 are independently hydrogen, alkyl or aryl; B is a carbocyclic or heterocyclic ring system, and E is amino, substituted amino such as alkylamino or arylamino, or piperidino. The compounds are stated to be useful as intermediates in the preparation of triphenylmethane dyes.
M. Scholtz, Chem. Ber. 46, 2138-2146 (1913), discloses o-hydroxyphenyl-piperidino-.alpha.-methylindolyl-methane and [2-hydroxy-5-methyl-phenyl]-piperidino-.alpha.-methylindolyl-methane prepared by reacting salicylaldehyde or p-homosalicylaldehyde with .alpha.-methylindole and piperidine. No utility is disclosed for these compounds.
R. W. Huffman and T. C. Bruice, J. Amer. Chem. Soc. 89, 6243-6251 (1967), disclose phenyl-3-(2-methylindolyl)morpholinomethane and phenyl-3-(2-methylindolyl)piperidinomethane as reaction products in a kinetic study.
C. W. Rees and C. R. Sabet, J. Chem. Soc., 687-691 (1965), disclose 3-(.alpha.-anilinobenzyl)-2-methylindole. No utility is disclosed for the compound.
V. N. Rusinova et al., Tr. Mosk. Khim.-Tekhnol. Inst. No. 66, 125-128 (1970); Chem. Abstracts 75, 88430x (1971), disclose 3-[(methylamino)(phenyl)methyl]indole. No utility is disclosed for the compound.